time

(Last Updated On: 7. September 2018)

info und man gehören zu den von mir am häufigsten genutzten Befehlen auf meinem Ubuntu. Manchmal möchte ich aber auch auf meinem Handy oder auf einem fremden PC nachlesen und daher kopiere ich mir manche Auszüge von info und man hier her. Ich sammle diese Artikel in der Kategorie „Linux“, „GNU-Handbücher“ und Subkategorie, wie für „time“ die Kategorie „Sys-Admin“.

Wenn „which time“ „/usr/bin/time“ sagt, wird die GNU-Version verwendet, sonst kann man das erreichen mit:
# The following methods bypass the built-in ‚time‘ and use GNU time:
$ env time make
$ /usr/bin/time make
$ \time make


man von time:
TIME(1) General Commands Manual TIME(1)

NAME
time – run programs and summarize system resource usage

SYNOPSIS
time [ -apqvV ] [ -f FORMAT ] [ -o FILE ]
[ –append ] [ –verbose ] [ –quiet ] [ –portability ]
[ –format=FORMAT ] [ –output=FILE ] [ –version ]
[ –help ] COMMAND [ ARGS ]

DESCRIPTION
time run the program COMMAND with any given arguments ARG…. When
COMMAND finishes, time displays information about resources used by
COMMAND (on the standard error output, by default). If COMMAND exits
with non-zero status, time displays a warning message and the exit
status.

time determines which information to display about the resources used
by the COMMAND from the string FORMAT. If no format is specified on
the command line, but the TIME environment variable is set, its value
is used as the format. Otherwise, a default format built into time is
used.

Options to time must appear on the command line before COMMAND.
Anything on the command line after COMMAND is passed as arguments to
COMMAND.

OPTIONS
-o FILE, –output=FILE
Write the resource use statistics to FILE instead of to the
standard error stream. By default, this overwrites the file,
destroying the file’s previous contents. This option is useful
for collecting information on interactive programs and programs
that produce output on the standard error stream.

-a, –append
Append the resource use information to the output file instead
of overwriting it. This option is only useful with the `-o‘ or
`–output‘ option.

-f FORMAT, –format FORMAT
Use FORMAT as the format string that controls the output of
time. See the below more information.

–help Print a summary of the command line options and exit.

-p, –portability
Use the following format string, for conformance with POSIX
standard 1003.2:
real %e
user %U
sys %S

-v, –verbose
Use the built-in verbose format, which displays each available
piece of information on the program’s resource use on its own
line, with an English description of its meaning.

–quiet
Do not report the status of the program even if it is different
from zero.

-V, –version
Print the version number of time and exit.

FORMATTING THE OUTPUT
The format string FORMAT controls the contents of the time output. The
format string can be set using the `-f‘ or `–format‘, `-v‘ or
`–verbose‘, or `-p‘ or `–portability‘ options. If they are not
given, but the TIME environment variable is set, its value is used as
the format string. Otherwise, a built-in default format is used. The
default format is:
%Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
%Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps

The format string usually consists of `resource specifiers‘
interspersed with plain text. A percent sign (`%‘) in the format
string causes the following character to be interpreted as a resource
specifier, which is similar to the formatting characters in the
printf(3) function.

A backslash (`\‘) introduces a `backslash escape‘, which is translated
into a single printing character upon output. `\t‘ outputs a tab
character, `\n‘ outputs a newline, and `\\‘ outputs a backslash. A
backslash followed by any other character outputs a question mark (`?‘)
followed by a backslash, to indicate that an invalid backslash escape
was given.

Other text in the format string is copied verbatim to the output. time
always prints a newline after printing the resource use information, so
normally format strings do not end with a newline character (or `\n‘).

There are many resource specifications. Not all resources are measured
by all versions of Unix, so some of the values might be reported as
zero. Any character following a percent sign that is not listed in the
table below causes a question mark (`?‘) to be output, followed by that
character, to indicate that an invalid resource specifier was given.

The resource specifiers, which are a superset of those recognized by
the tcsh(1) builtin `time‘ command, are:
% A literal `%‘.
C Name and command line arguments of the command being
timed.
D Average size of the process’s unshared data area, in
Kilobytes.
E Elapsed real (wall clock) time used by the process, in
[hours:]minutes:seconds.
F Number of major, or I/O-requiring, page faults that
occurred while the process was running. These are faults
where the page has actually migrated out of primary
memory.
I Number of file system inputs by the process.
K Average total (data+stack+text) memory use of the
process, in Kilobytes.
M Maximum resident set size of the process during its
lifetime, in Kilobytes.
O Number of file system outputs by the process.
P Percentage of the CPU that this job got. This is just
user + system times divided by the total running time.
It also prints a percentage sign.
R Number of minor, or recoverable, page faults. These are
pages that are not valid (so they fault) but which have
not yet been claimed by other virtual pages. Thus the
data in the page is still valid but the system tables
must be updated.
S Total number of CPU-seconds used by the system on behalf
of the process (in kernel mode), in seconds.
U Total number of CPU-seconds that the process used
directly (in user mode), in seconds.
W Number of times the process was swapped out of main
memory.
X Average amount of shared text in the process, in
Kilobytes.
Z System’s page size, in bytes. This is a per-system
constant, but varies between systems.
c Number of times the process was context-switched
involuntarily (because the time slice expired).
e Elapsed real (wall clock) time used by the process, in
seconds.
k Number of signals delivered to the process.
p Average unshared stack size of the process, in Kilobytes.
r Number of socket messages received by the process.
s Number of socket messages sent by the process.
t Average resident set size of the process, in Kilobytes.
w Number of times that the program was context-switched
voluntarily, for instance while waiting for an I/O
operation to complete.
x Exit status of the command.

EXAMPLES
To run the command `wc /etc/hosts‘ and show the default information:
time wc /etc/hosts

To run the command `ls -Fs‘ and show just the user, system, and total
time:
time -f „\t%E real,\t%U user,\t%S sys“ ls -Fs

To edit the file BORK and have `time‘ append the elapsed time and
number of signals to the file `log‘, reading the format string from the
environment variable `TIME‘:
export TIME=“\t%E,\t%k“ # If using bash or ksh
setenv TIME „\t%E,\t%k“ # If using csh or tcsh
time -a -o log emacs bork

Users of the bash shell need to use an explicit path in order to run
the external time command and not the shell builtin variant. On system
where time is installed in /usr/bin, the first example would become
/usr/bin/time wc /etc/hosts

ACCURACY
The elapsed time is not collected atomically with the execution of the
program; as a result, in bizarre circumstances (if the time command
gets stopped or swapped out in between when the program being timed
exits and when time calculates how long it took to run), it could be
much larger than the actual execution time.

When the running time of a command is very nearly zero, some values
(e.g., the percentage of CPU used) may be reported as either zero
(which is wrong) or a question mark.

Most information shown by time is derived from the wait3(2) system
call. The numbers are only as good as those returned by wait3(2). On
systems that do not have a wait3(2) call that returns status
information, the times(2) system call is used instead. However, it
provides much less information than wait3(2), so on those systems time
reports the majority of the resources as zero.

The `%I‘ and `%O‘ values are allegedly only `real‘ input and output and
do not include those supplied by caching devices. The meaning of
`real‘ I/O reported by `%I‘ and `%O‘ may be muddled for workstations,
especially diskless ones.

DIAGNOSTICS
The time command returns when the program exits, stops, or is
terminated by a signal. If the program exited normally, the return
value of time is the return value of the program it executed and
measured. Otherwise, the return value is 128 plus the number of the
signal which caused the program to stop or terminate.
AUTHOR
time was written by David MacKenzie. This man page was added by Dirk
Eddelbuettel , the Debian GNU/Linux maintainer, for use
by the Debian GNU/Linux distribution but may of course be used by
others.

SEE ALSO
tcsh(1), printf(3)

Debian GNU/Linux TIME(1)


info von time:
File: time.info, Node: Top, Next: Resource Measurement, Up: (dir)

The GNU ‚time‘ Command
**********************

This file documents the the GNU ‚time‘ command for running programs and
summarizing the system resources they use. This is edition 1.7, for
version 1.7.

* Menu:

* Resource Measurement:: Measuring program resource use.
* Concept index:: Index of concepts.

File: time.info, Node: Resource Measurement, Next: Concept index, Prev: Top, Up: Top

1 Measuring Program Resource Use
********************************

The ‚time‘ command runs another program, then displays information about
the resources used by that program, collected by the system while the
program was running. You can select which information is reported and
the format in which it is shown (*note Setting Format::), or have ‚time‘
save the information in a file instead of displaying it on the screen
(*note Redirecting::).

The resources that ‚time‘ can report on fall into the general
categories of time, memory, and I/O and IPC calls. Some systems do not
provide much information about program resource use; ‚time‘ reports
unavailable information as zero values (*note Accuracy::).

The format of the ‚time‘ command is:

time [option…] COMMAND [ARG…]

‚time‘ runs the program COMMAND, with any given arguments ARG….
When COMMAND finishes, ‚time‘ displays information about resources used
by COMMAND.

Here is an example of using ‚time‘ to measure the time and other
resources used by running the program ‚grep‘:

eg$ time grep nobody /etc/aliases
nobody:/dev/null
etc-files:nobody
misc-group:nobody
0.07user 0.50system 0:06.69elapsed 8%CPU (0avgtext+489avgdata 324maxresident)k
46inputs+7outputs (43major+251minor)pagefaults 0swaps

Mail suggestions and bug reports for GNU ‚time‘ to
‚bug-gnu-utils@gnu.org‘. Please include the version of ‚time‘, which
you can get by running ‚time –version‘, and the operating system and C
compiler you used.

* Menu:

* Setting Format:: Selecting the information reported by ‚time‘.
* Format String:: The information ‚time‘ can report.
* Redirecting:: Writing the information to a file.
* Examples:: Examples of using ‚time‘.
* Accuracy:: Limitations on the accuracy of ‚time‘ output.
* Invoking time:: Summary of the options to the ‚time‘ command.

File: time.info, Node: Setting Format, Next: Format String, Up: Resource Measurement

1.1 Setting the Output Format
=============================

‚time‘ uses a „format string“ to determine which information to display
about the resources used by the command it runs. *Note Format String::,
for the interpretation of the format string contents.

You can specify a format string with the command line options listed
below. If no format is specified on the command line, but the ‚TIME‘
environment variable is set, its value is used as the format string.
Otherwise, the default format built into ‚time‘ is used:

%Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
%Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps

The command line options to set the format are:

‚-f FORMAT‘
‚–format=FORMAT‘
Use FORMAT as the format string.

‚-p‘
‚–portability‘
Use the following format string:

real %e
user %U
sys %S

The default output format of time differs widely between
implementations. This option (in its short form -p) is supported
by all POSIX-compliant ‚time‘ implementations to retrieve basic
information in the described format.

‚-q‘
‚–quiet‘
Suppress non-zero error code from the executed program.

‚-v‘
‚–verbose‘
Use the built-in verbose format, which displays each available
piece of information on the program’s resource use on its own line,
with an English description of its meaning.

File: time.info, Node: Format String, Next: Redirecting, Prev: Setting Format, Up: Resource Measurement

1.2 The Format String
=====================

The „format string“ controls the contents of the ‚time‘ output. It
consists of „resource specifiers“ and „escapes“, interspersed with plain
text.

A backslash introduces an „escape“, which is translated into a single
printing character upon output. The valid escapes are listed below. An
invalid escape is output as a question mark followed by a backslash.

‚\t‘
a tab character

‚\n‘
a newline

‚\\‘
a literal backslash

‚time‘ always prints a newline after printing the resource use
information, so normally format strings do not end with a newline
character (or ‚\n‘).

A resource specifier consists of a percent sign followed by another
character. An invalid resource specifier is output as a question mark
followed by the invalid character. Use ‚%%‘ to output a literal percent
sign.

The resource specifiers, which are a superset of those recognized by
the ‚tcsh‘ builtin ‚time‘ command, are listed below. Not all resources
are measured by all versions of Unix, so some of the values might be
reported as zero (*note Accuracy::).

* Menu:

* Time Resources::
* Memory Resources::
* I/O Resources::
* Command Info::

File: time.info, Node: Time Resources, Next: Memory Resources, Up: Format String

1.2.1 Time Resources
——————–

‚E‘
Elapsed real (wall clock) time used by the process, in
[hours:]minutes:seconds.

‚e‘
Elapsed real (wall clock) time used by the process, in seconds.

‚S‘
Total number of CPU-seconds used by the system on behalf of the
process (in kernel mode), in seconds.

‚U‘
Total number of CPU-seconds that the process used directly (in user
mode), in seconds.

‚P‘
Percentage of the CPU that this job got. This is just user +
system times divied by the total running time.

File: time.info, Node: Memory Resources, Next: I/O Resources, Prev: Time Resources, Up: Format String

1.2.2 Memory Resources
———————-

‚M‘
Maximum resident set size of the process during its lifetime, in
Kilobytes.

‚t‘
Average resident set size of the process, in Kilobytes.

‚K‘
Average total (data+stack+text) memory use of the process, in
Kilobytes.

‚D‘
Average size of the process’s unshared data area, in Kilobytes.

‚p‘
Average size of the process’s unshared stack, in Kilobytes.

‚X‘
Average size of the process’s shared text, in Kilobytes.

‚Z‘
System’s page size, in bytes. This is a per-system constant, but
varies between systems.

File: time.info, Node: I/O Resources, Next: Command Info, Prev: Memory Resources, Up: Format String

1.2.3 I/O Resources
——————-

‚F‘
Number of major, or I/O-requiring, page faults that occurred while
the process was running. These are faults where the page has
actually migrated out of primary memory.

‚R‘
Number of minor, or recoverable, page faults. These are pages that
are not valid (so they fault) but which have not yet been claimed
by other virtual pages. Thus the data in the page is still valid
but the system tables must be updated.

‚W‘
Number of times the process was swapped out of main memory.

‚c‘
Number of times the process was context-switched involuntarily
(because the time slice expired).

‚w‘
Number of times that the program was context-switched voluntarily,
for instance while waiting for an I/O operation to complete.

‚I‘
Number of file system inputs by the process.

‚O‘
Number of file system outputs by the process.

‚r‘
Number of socket messages received by the process.

’s‘
Number of socket messages sent by the process.

‚k‘
Number of signals delivered to the process.

File: time.info, Node: Command Info, Prev: I/O Resources, Up: Format String

1.2.4 Command Info
——————

‚C‘
Name and command line arguments of the command being timed.

‚x‘
Exit status of the command.

File: time.info, Node: Redirecting, Next: Examples, Prev: Format String, Up: Resource Measurement

1.3 Redirecting Output
======================

By default, ‚time‘ writes the resource use statistics to the standard
error stream. The options below make it write the statistics to a file
instead. Doing this can be useful if the program you’re running writes
to the standard error or you’re running ‚time‘ noninteractively or in
the background.

‚-o FILE‘
‚–output=FILE‘
Write the resource use statistics to FILE. By default, this
_overwrites_ the file, destroying the file’s previous contents.

‚-a‘
‚–append‘
_Append_ the resource use information to the output file instead of
overwriting it. This option is only useful with the ‚-o‘ or
‚–output‘ option.

File: time.info, Node: Examples, Next: Accuracy, Prev: Redirecting, Up: Resource Measurement

1.4 Examples
============

Run the command ‚wc /etc/hosts‘ and show the default information:

eg$ time wc /etc/hosts
35 111 1134 /etc/hosts
0.00user 0.01system 0:00.04elapsed 25%CPU (0avgtext+0avgdata 0maxresident)k
1inputs+1outputs (0major+0minor)pagefaults 0swaps

Run the command ‚ls -Fs‘ and show just the user, system, and wall-clock
time:

eg$ time -f „\t%E real,\t%U user,\t%S sys“ ls -Fs
total 16
1 account/ 1 db/ 1 mail/ 1 run/
1 backups/ 1 emacs/ 1 msgs/ 1 rwho/
1 crash/ 1 games/ 1 preserve/ 1 spool/
1 cron/ 1 log/ 1 quotas/ 1 tmp/
0:00.03 real, 0.00 user, 0.01 sys

Edit the file ‚.bashrc‘ and have ‚time‘ append the elapsed time and
number of signals to the file ‚log‘, reading the format string from the
environment variable ‚TIME‘:

eg$ export TIME=“\t%E,\t%k“ # If using bash or ksh
eg$ setenv TIME „\t%E,\t%k“ # If using csh or tcsh
eg$ time -a -o log emacs .bashrc
eg$ cat log
0:16.55, 726

Run the command ’sleep 4′ and show all of the information about it
verbosely:

eg$ time -v sleep 4
Command being timed: „sleep 4“
User time (seconds): 0.00
System time (seconds): 0.05
Percent of CPU this job got: 1%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:04.26
Average shared text size (kbytes): 36
Average unshared data size (kbytes): 24
Average stack size (kbytes): 0
Average total size (kbytes): 60
Maximum resident set size (kbytes): 32
Average resident set size (kbytes): 24
Major (requiring I/O) page faults: 3
Minor (reclaiming a frame) page faults: 0
Voluntary context switches: 11
Involuntary context switches: 0
Swaps: 0
File system inputs: 3
File system outputs: 1
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 1
Page size (bytes): 4096
Exit status: 0

File: time.info, Node: Accuracy, Next: Invoking time, Prev: Examples, Up: Resource Measurement

1.5 Accuracy
============

The elapsed time is not collected atomically with the execution of the
program; as a result, in bizarre circumstances (if the ‚time‘ command
gets stopped or swapped out in between when the program being timed
exits and when ‚time‘ calculates how long it took to run), it could be
much larger than the actual execution time.

When the running time of a command is very nearly zero, some values
(e.g., the percentage of CPU used) may be reported as either zero (which
is wrong) or a question mark.

Most information shown by ‚time‘ is derived from the ‚wait3‘ system
call. The numbers are only as good as those returned by ‚wait3‘. Many
systems do not measure all of the resources that ‚time‘ can report on;
those resources are reported as zero. The systems that measure most or
all of the resources are based on 4.2 or 4.3BSD. Later BSD releases use
different memory management code that measures fewer resources.

On systems that do not have a ‚wait3‘ call that returns status
information, the ‚times‘ system call is used instead. It provides much
less information than ‚wait3‘, so on those systems ‚time‘ reports most
of the resources as zero.

The ‚%I‘ and ‚%O‘ values are allegedly only „real“ input and output
and do not include those supplied by caching devices. The meaning of
„real“ I/O reported by ‚%I‘ and ‚%O‘ may be muddled for workstations,
especially diskless ones.

File: time.info, Node: Invoking time, Prev: Accuracy, Up: Resource Measurement

1.6 Running the ‚time‘ Command
==============================

The format of the ‚time‘ command is:

time [option…] COMMAND [ARG…]

‚time‘ runs the program COMMAND, with any given arguments ARG….
When COMMAND finishes, ‚time‘ displays information about resources used
by COMMAND (on the standard error output, by default). If COMMAND exits
with non-zero status or is terminated by a signal, ‚time‘ displays a
warning message and the exit status or signal number.

Options to ‚time‘ must appear on the command line before COMMAND.
Anything on the command line after COMMAND is passed as arguments to
COMMAND.

‚-o FILE‘
‚–output=FILE‘
Write the resource use statistics to FILE.

‚-a‘
‚–append‘
_Append_ the resource use information to the output file instead of
overwriting it.

‚-f FORMAT‘
‚–format=FORMAT‘
Use FORMAT as the format string.

‚–help‘
Print a summary of the command line options to ‚time‘ and exit.

‚-p‘
‚–portability‘
Use the POSIX format.

‚-v‘
‚–verbose‘
Use the built-in verbose format.

‚-V‘
‚–version‘
Print the version number of ‚time‘ and exit.

File: time.info, Node: Concept index, Prev: Resource Measurement, Up: Top

Concept index
*************

* Menu:

* error (in measurement): Accuracy. (line 6)
* format: Format String. (line 6)
* resource specifiers: Resource Measurement. (line 22)
* resources: Invoking time. (line 10)
* time invocation: Resource Measurement. (line 6)
* verbose format: Setting Format. (line 43)
* verbose option: Invoking time. (line 42)
* version number: Invoking time. (line 46)


Weblinks:
http://www.gnu.org/manual/
System-administrationhttps://shop.fsf.org/collection/books-docs

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